The present invention relates to a method of head positioning in an information recording device such as a magnetic disk device, a floppy disk device, a magnetic tape device, an opto-magnetic disk device and a magnetic card device, and a magnetic recording disk drive using this method. More particularly, the present invention relates for technology suitable to a large capacity disk drive with high track density, and for positioning a head on a target data track with high accuracy.
In order to read information recorded on a magnetic medium with high accuracy, a signal conversion device, for example, a magnetic head must be positioned with high accuracy on the target of the recording position of a recording medium. However, the positioning becomes very difficult with increase of the track density. So, it is preferable that a servo signal is located in the extreme neighborhood of the target data track. Such an idea of a data embedded servo for locating a servo signal on the data surface is included in a system of sector servo or buried servo in a magnetic disk device, a floppy disk device, etc. having a rotary recording medium. In the sector servo system, the positioning accuracy is greatly influenced by the number of sectors, and the frequency bands of the servo system is also limited. The buried servo system is more favorable to improve the positioning accuracy than the sector servo system in terms of that the former is not a serial servo system. In the buried servo system, as disclosed in IEEE Transaction on Magnetics Mag.-176, the frequency bands for a data signal and a servo signal are discriminated so that both signals can be accurately separated in such a manner that the recording frequency of the data signal to be recorded on the upper layer of a recording medium is several MHz and that of the servo signal to be recorded on the lower layer is several hundred KHz.